更改 ADT 数组中一项中的字段的问题

Question

我正在尝试编辑 Person[] 数组中的一项，但由于某种原因，每当调用 setHasVirus 时，整个数组都会更改为“有病毒”。从字面上看，每个项目的 hasVirus 变量都从 false 更改为 true。我试图只编辑第二个项目，但它不起作用。你能告诉我有什么问题吗？

class Person{
    boolean vaccine;
    boolean hasVirus;
    boolean alive;
}

class arrayADT{
    Person[] people;
    int count; 
}




public static String inputString(String message)
    {
        Scanner scanner = new Scanner(System.in);
        System.out.println(message);
        return scanner.nextLine();
    }
    
    public static int inputInt(String message)
    {
        return Integer.parseInt(inputString(message));
    }
    
    public static int inputIntRange(String message, int min, int max)
    {
        int result = Integer.parseInt(inputString(message));
        while((result < min) | (result > max))
        {
            result = Integer.parseInt(inputString(message));
        }
    return result;
    }
    
    public static Person setVaccine(Person a, boolean b){ //accessor method
        a.vaccine = b;
        return a;
    }
    
    public static Person setHasVirus(Person a, boolean b){ //accessor method
        a.hasVirus = b;
        return a;
    }
    
    public static Person setAlive(Person a, boolean b){ //accessor method
        a.alive = b;
        return a;
    }
    
    public static Person createPatient(boolean a, boolean b, boolean c){ //initialises the object
        Person d = new Person();
        d = setVaccine(d, a);
        d = setHasVirus(d, b);
        d = setAlive(d, c);
        return d;
    }

public static Person getSingleRecord(arrayADT ap, int number) 
    { 
        return ap.people[number]; 
    }

public static arrayADT addPatientRecord(arrayADT ap, Person a) //adds one record to the existing array adt
    {
        ap.people[ap.count] = a; 
        ap.count = ap.count + 1; 
        return ap;     
    }

public static arrayADT inputPeople(){
arrayADT a = new arrayADT();
int howMany = inputIntRange("Number of people to simulate?(between 100 and 1000)", 100, 1000);
a.people = new Person[howMany];
Person d = createPatient(false, false, true);
        for(int i = 0; i<howMany; i++){
            addPatientRecord(a, d); //filling out the array with default values
        }
setHasVirus(getSingleRecord(a, 2),true); //trying to edit only one item in the whole array
return a;
}

Answer 1

这是因为您只创建了 Person 的 1 个实例，并用指向这个实例的指针填充了整个数组。

为了修复您描述的行为，您需要为每个数组条目创建一个单独的实例：

// ...
  for(int i = 0; i<howMany; i++) {
    Person p = createPatient(false, false, true); //filling out the array with default values
    addPatientRecord(a, p); 
  }
// ...

更改 ADT 数组中一项中的字段的问题

Problem with changing a field in one item in an ADT array

java

arrays

methods